# Compound Interest Eqns Help: 'If a bacteria colony grows...'

#### agreen37

##### New member
Maybe some don't mind helping me with this brain teaser. I attempted the problem. Plugging and plugging....I'm getting the incorrect answer. Can you? Here's the question:

A colony of bacteria numbers 100. If the population grows at a rate of 50% per hour, compounded hourly, what will it be in 8 hours?...

Plesae help me solve this. I've been at it for 2days now.... :roll:

Thanks a bunch!

AnG'

#### TchrWill

##### Full Member
Re: Compound Interest Equations Help

agreen37 said:
A colony of bacteria numbers 100. If the population grows at a rate of 50% per hour, compounded hourly, what will it be in 8 hours?
This is no different than the growth of an amount of money in a bank.

A scecific deposit called the principal will grow to S = P(1 + i)^n.

In your case, P = 100, i = the periodic interest, or growth, rate, .50, and n = the number of compounding periods, 8.

Therefore, S = 100(1.5)^8 = 2562.89.

#### Denis

##### Senior Member
or you can multiply 8 times:
100 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 = 2562.890625

TchrWill's 100 * (1.5)^8 is the same thing :idea:

#### agreen37

##### New member
Re: Compound Interest Equations Help

Thank you, TchrWill. That did it! I appreciate your assistance!

#### agreen37

##### New member
Got it!! Denis, love "your qoute!" Thanks.

Denis said:
or you can multiply 8 times:
100 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 * 1.5 = 2562.890625

TchrWill's 100 * (1.5)^8 is the same thing :idea: